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It will give way. It's a matter of time. Everyone I know with a SC'd 3L M54 engine have problems with their step tranny. It will slip, refuse to shift up to 5th...etc. We're talking SK1 and above kits. Maybe the tranny can still take it with an SK+ kit. Don't know for sure.

They either rebuild it adding additional clutch plates or swap to manual.

Or you could drive your car really gently, which defeats the whole purpose of SC...

My car is a 320i with an SK1 kit with an 11PSI pulley. I swapped my 320i step tranny with an 330i step tranny. It's holding up ok but I can feel I'm really pushing the limit already. I run an ATF cooler to help prolong the life, but the torque output of my engine is already much more than the rating for a 330i step tranny. So you can imagine how much more torque an 3L engine will push out...

from what i've gathered reading on here and other sites, from tuners to experienced individuals (Mr Paddle.Shift, MarvelPhx amongst others), keeping the power output at about ~300 hp and torque at ~295 lbs/ft (or lower) is the general consensus if you want to keep your transmission for a while. this power is achieved with a 5.5 or 6 psi pulley. there are certain ZF transmission models that handle high power better than others, Alpina uses one such ZF transmission in one of their cars (don't remember the exact transmission model - Mr Paddle.Shift does).

then there are members who have 330s @ 6.5 psi producing 330 hp (Shinobi) who has had no problems this far, and others with the same kit but headers and/or cams in addition who's had their transmissions fail.

personally i'd go with 300 hp to play it safe(r) - i put "safer" because there are no guarantees.

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BBS | ACS"if you wanna be king of the ring, this is the kind of car you should get" -M3 CSL"there's no replacement for displacement" - only BMW ///M

from what i've gathered reading on here and other sites, from tuners to experienced individuals (Mr Paddle.Shift, MarvelPhx amongst others), keeping the power output at about ~300 hp and torque at ~295 lbs/ft (or lower) is the general consensus if you want to keep your transmission for a while. this power is achieved with a 5.5 or 6 psi pulley. there are certain ZF transmission models that handle high power better than others, Alpina uses one such ZF transmission in one of their cars (don't remember the exact transmission model - Mr Paddle.Shift does).

then there are members who have 330s @ 6.5 psi producing 330 hp (Shinobi) who has had no problems this far, and others with the same kit but headers and/or cams in addition who's had their transmissions fail.

personally i'd go with 300 hp to play it safe(r) - i put "safer" because there are no guarantees.

i've read up on this subject because it's interesting, because i'd like to get supercharged and because you learn a lot about your car from reading about forced induction (not only power figures ). with a steptronic transmission you really need to know what you're getting yourself into, what to expect and how to not blow up your transmission.

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BBS | ACS"if you wanna be king of the ring, this is the kind of car you should get" -M3 CSL"there's no replacement for displacement" - only BMW ///M

i've read up on this subject because it's interesting, because i'd like to get supercharged and because you learn a lot about your car from reading about forced induction (not only power figures ). with a steptronic transmission you really need to know what you're getting yourself into, what to expect and how to not blow up your transmission.

I have the sk+ kit at 6.5 psi. Probably right around 300-310 chp. Dynoed at 245 at 5.5psi. Should be somewhere in the neighborhood of 255 right now. Its been running awesome for almost a year now. I can probably slap on some headers too, but don't want the car too loud.

I have the sk+ kit at 6.5 psi. Probably right around 300-310 chp. Dynoed at 245 at 5.5psi. Should be somewhere in the neighborhood of 255 right now. Its been running awesome for almost a year now. I can probably slap on some headers too, but don't want the car too loud.